Disposable safety syringe

Abstract

A safety syringe 10 includes a generally tubular body 14 having a needle end 18 and plunger end 22 , needle 38 and retractable needle seat 30 , two-way valve 36 , plunger 42 , stopper 62 , piston 52 , and rear plunger seal 44 . During use, the plunger may be moved to create a vacuum in the plunger. The user then moves the plunger toward the needle end, pressurizing a vial, then pulls backward to a selected position corresponding to the desired volume of fluid to be withdrawn. At the conclusion of the injection stroke, the piston is disengaged from the plunger. The vacuum within the plunger retracts the needle safely into the tubular body.

1. A syringe for retracting a needle supported on a needle seat, comprising:
 a generally tubular body having a needle end and an opposing plunger end, the tubular body having an internal throughbore extending between the needle end and the opposing plunger end, the tubular body sealing receiving the needle seat therein;  
 a seat/body retainer adjacent the needle end of the tubular body for initially attaching the needle seat to the generally tubular body, the needle seat being selectively moveable within the tubular body from an initial retained position to a needle seat retracted position;  
 a plunger having an interior chamber therein and a needle seat end positioned within the internal throughbore of the generally tubular body, the plunger being moveable within the throughbore of the tubular body;  
 a stopper for sealed engagement between the generally tubular body and the plunger;  
 a piston selectively moveable between an initial retained position adjacent the needle seat end of the plunger and a piston retracted position within the plunger;  
 a one-way valve allowing flow from the interior chamber in the plunger to the throughbore in the generally tubular body while preventing fluid flow from the throughbore in the generally tubular body to the interior chamber in the plunger;  
 a seat/piston latch for selective engagement of the needle seat with the piston; and  
 a controllable plug selectively preventing fluid from entering the tubular body through the needle end when in a closed position.  
 
   
   
     2. A syringe as defined in  claim 1 , wherein the one-way valve comprises one or more through ports in the plunger, and the stopper is moveable relative to the one or more ports between a closed position for closing off flow through the ports and an open position for opening the ports to create a partial vacuum within the plunger interior chamber. 
   
   
     3. A syringe as defined in  claim 2 , wherein the stopper automatically moves radially outward to the open position in response to reduced pressure in the tubular body throughbore compared to pressure in the interior chamber in the plunger. 
   
   
     4. A syringe as defined in  claim 1 , wherein the piston is selectively retained in the initial retained position by a piston/plunger retainer, and the piston engages the needle seat to disengage the piston/plunger retainer and release the piston to move away from the needle seat end of the plunger. 
   
   
     5. A syringe as defined in  claim 1 , wherein:
 the seat/piston latch includes one of a male connector and a female connector secured to the plunger and the other of the male connector and the female connector secured to the piston.  
 
   
   
     6. The syringe as defined in  claim 1 , further comprising:
 graduations on the, tubular body increasing from the needle end toward the plunger end.  
 
   
   
     7. A syringe as defined in  claim 1 , further comprising:
 a plate secured to a plate end of the plunger for applying an axial force to the plunger.  
 
   
   
     8. A syringe as defined in  claim 1 , wherein the stopper is axially secured to and moveable with the plunger. 
   
   
     9. A syringe as defined in  claim 1 , further comprising:
 a stop secured to the tubular body for preventing the plunger from coming fully out of the tubular body.  
 
   
   
     10. A syringe as defined in  claim 1 , wherein the controllable plug is a manually removed plug. 
   
   
     11. A syringe as defined in  claim 10 , wherein the removable plug seals a needle supported on the tubular body end, and is manually removed subsequent to creating a vacuum with the plunger. 
   
   
     12. A syringe as defined in  claim 10 , wherein the removable plug seals the needle end of the tubular body and is manually removed subsequent to creating a vacuum within the plunger. 
   
   
     13. A syringe as defined in  claim 1 , wherein movement of the plunger to an injection position expands a portion of a generally tubular body to release the seat/body retainer and the needle seat from the tubular body. 
   
   
     14. A syringe as defined in  claim 1 , wherein a seal between the needle seat and the tubular body retains the needle seat in the initial retained position, and movement of the plunger to an injection position moves the seal such that the needle seat is released from the generally tubular body. 
   
   
     15. A syringe for retracting a needle supported on a needle seat, comprising:
 a generally tubular body having a needle end and an opposing plunger end, the tubular body having an internal throughbore extending between the needle end and the opposing plunger end, the tubular body sealing receiving the needle seat therein;  
 a seat/body retainer adjacent the needle end of the tubular body for initially attaching the needle seat to the generally tubular body, the needle seat being selectively moveable within the tubular body from an initial retained position to a needle seat retracted position;  
 a plunger having an interior chamber therein and a needle seat end positioned within the internal throughbore of the generally tubular body, the plunger being sealed to the tubular body and moveable within the throughbore of the tubular body;  
 a piston selectively moveable between an initial retained position adjacent the needle seat end of the plunger and a piston retracted position within the plungers the piston being selectively retained in the initial retained position by a piston/plunger retainer, and the piston engages the needle seat to disengage the piston/plunger retainer and release the piston to move away from the needle seat end of the plunger;  
 a one-way valve allowing flow from the interior chamber in the plunger to the throughbore in the generally tubular body while preventing fluid flow from the throughbore in the generally tubular body to the interior chamber in the plunger, a seat/piston latch for selective engagement of the needle seat with the piston; and  
 a controllable plug selectively preventing fluid from entering the tubular body through the needle end when in a closed position.  
 
   
   
     16. A syringe is defined in  claim 15 , wherein the piston/plunger retainer includes a shoulder on one of the piston and the plunger for positioning within a groove on the other of the piston and the plunger when the piston is in the initial retained position. 
   
   
     17. A syringe as defined in  claim 15 , wherein the one-way valve comprises one or more through ports in the plunger, and a stopper which seals between the body and the plunger is moveable relative to the one or more ports between a closed position for closing off flow through the ports and an open position for opening the ports to create a partial vacuum within the plunger interior chamber. 
   
   
     18. A syringe as defined in  claim 15 , wherein the seat/piston latch includes one of a male connector and a female connector secured to the plunger and the other of the male connector and the female connector secured to the piston. 
   
   
     19. A syringe as defined in  claim 15 , wherein the controllable plug seals a needle supported on the tubular body and is manually removed subsequent to creating a vacuum within the plunger. 
   
   
     20. A syringe as defined in  claim 15 , wherein movement of the plunger to an injection position expands a portion of a generally tubular body to release the seat/body retainer and the needle seat from the tubular body. 
   
   
     21. A syringe as defined in  claim 15 , wherein a seal between the needle seat and the tubular body retains the needle seat in the initial retained position, and movement of the plunger to an injection position moves the seal such that the needle seat is released from the generally tubular body. 
   
   
     22. A syringe for retracting a needle supported on a needle seat, comprising:
 a generally tubular body having a needle end and an opposing plunger end, the tubular body having an internal throughbore extending between the needle end and the opposing plunger end, the tubular body sealing receiving the needle seat therein;  
 a seat/body retainer adjacent the needle end of the tubular body for initially attaching the needle seat to the generally tubular body, the needle seat being selectively moveable within the tubular body from an initial retained position to a needle seat retracted position;  
 a plunger having an interior chamber therein and a needle seat end positioned within the internal throughbore of the generally tubular body, the plunger being sealed to the tubular body and moveable within the throughbore of the tubular body;  
 a piston selectively moveable between an initial retained position adjacent to the needle seat end of the plunger and a piston retracted position within the plunger;  
 a one-way valve allowing flow from the interior chamber in the plunger to the throughbore in the generally tubular body while preventing fluid flow from the throughbore in the generally tubular body to the interior chamber in the plunger;  
 a seat/piston latch including one of a male connector and a female connector secured to the plunger and the other of the male connector and the female connector secured to the piston for selective engagement of the needle seat with the piston; and  
 a controllable plug selectively preventing fluid from entering the tubular body through the needle end when in a closed position.  
 
   
   
     23. A syringe as defined in  claim 22 , wherein the one-way valve comprises one or more through ports in the plunger, and a stopper which seals between the body and the plunger is moveable relative to the one or more ports between a closed position for closing off flow through the ports and an open position for opening the ports to create a partial vacuum within the plunger interior chamber. 
   
   
     24. A syringe as defined in  claim 22 , further comprising:
 graduations on the tubular body increasing from the needle end toward the plunger end; and  
 a plate secured to a plate end of the plunger for applying an axial force to the plunger.  
 
   
   
     25. A syringe as defined in  claim 22 , wherein movement of the plunger to an injection position expands a portion of a generally tubular body to release the seat/body retainer and the needle seat from the tubular body. 
   
   
     26. A syringe as defined in  claim 22 , wherein a seal between the needle seat and the tubular body retains the needle seat in the initial retained position, and movement of the plunger to an injection position moves the seal such that the needle seat is released from the generally tubular body. 
   
   
     27. A method of using a syringe with a needle seat supporting a needle retractable in a generally tubular body having an internal throughbore extending between a needle end and an opposing plunger end, the method comprising:
 sealingly engaging the needle seat with the generally tubular body, the needle seat being selectively movable from an initial retained position to a needle seat retracted position;  
 releasably retaining the needle seat in the initial retained position;  
 axially securing a stopper to a plunger within the throughbore of the tubular body;  
 positioning the plunger at least partially within the throughbore of the tubular body, the plunger including an internal chamber therein;  
 positioning a piston within the plunger moveable from an initial position in the needle end of the plunger to a retracted position within the internal chamber in the plunger;  
 providing a one-way valve between the internal chamber in the plunger and the throughbore of the generally tubular body;  
 plugging the needle seat end of the tubular body;  
 applying a first axial force to move the plunger from an initial position in the opposing plunger end of the tubular body to a selected displaced position, thereby creating a vacuum within the tubular body between needle end of the tubular body and the stopper and opening the one-way valve to obtain a vacuum within the plunger;  
 removing the plug in the needle seat end of the tubular body; inserting a needle into a liquid source;  
 withdrawing a selected volume of liquid from the liquid source through the needle and into the tubular body between the needle seat and the stopper while moving the plunger to a fluid drawn position;  
 thereafter inserting the needle into a fluid repository; thereafter applying a second axial force to the plunger to move the stopper toward the needle end of the tubular body while discharging liquid from within the tubular body;  
 engaging a seat/piston latch to axially connect the needle seat with the piston; and  
 relaxing the second force to disengage the needle seat from the generally tubular body and move the piston and the connected needle seat from the initial retained position to the needle seat retracted position.  
 
   
   
     28. A method as defined in  claim 27 , wherein the needle is inserted into the liquid source before moving the plunger to the displaced position, thereby pressurizing the liquid source while the plunger moves to the displaced position. 
   
   
     29. A method as defined in  claim 27 , wherein providing a one way valve includes providing one or more ports in the plunger, the stopper covering the one or more ports to close the valve when pressure within the body is greater than pressure within the plunger. 
   
   
     30. A method as defined in  claim 27 , wherein movement of the plunger to a full injection position releases the piston from a retained position on the plunger. 
   
   
     31. A method as defined in  claim 27 , further comprising:
 engaging the piston with the needle seat to release the piston from the plunger to move the piston axially away from the needle end of the plunger.  
 
   
   
     32. A method as defined in  claim 27 , wherein a wrapper encloses the tubular body to plug the needle end of the tubular body, and moving the plunger to create the vacuum opens the wrapper to unplug the needle end of the tubular body. 
   
   
     33. A method as defined in  claim 27 , further comprising:
 providing graduations on the tubular body increasing from the needle end toward the plunger end.  
 
   
   
     34. A method as defined in  claim 27 , further comprising:
 moving the plunger to an injection position such that the plunger expands a portion of the generally tubular body to release the needle seat.  
 
   
   
     35. A method as defined in  claim 27 , further comprising:
 moving the plunger to an injection position such that the plunger moves a seal between the seat and the tubular body to release the needle seat.  
 
   
   
     36. A method of using a syringe with a needle seat supporting a needle retractable in a generally tubular body having an internal throughbore extending between a needle end and an opposing plunger end, the method comprising:
 sealingly engaging the needle seat with the generally tubular body;  
 the needle seat being selectively movable from an initial retained position to a needle seat retracted position;  
 releasably retaining the needle seat in the initial retained position;  
 axially securing a stopper to a plunger within the throughbore of the tubular body;  
 positioning the plunger at least partially within the throughbore of the tubular body, the plunger including an internal chamber therein;  
 positioning a piston within the plunger moveable from an initial position in the needle end of the plunger to a retracted position within the internal chamber in the plunger, wherein the piston is selectively retained in the initial retained position by a piston/plunger retainer, and the piston engages the needle seat to disengage the piston/plunger retainer and release the piston to move away from the needle seat end of the plunger;  
 providing a one-way valve between the internal chamber in the plunger and the throughbore of the generally tubular body;  
 plugging the needle seat end of the tubular body;  
 applying a first axial force to move the plunger from an initial position in the opposing plunger end of the tubular body to a selected displaced position, thereby creating a vacuum within the tubular body between needle end of the tubular body and the stopper and opening the one-way valve to obtain a vacuum within the plunger;  
 removing the plug in the needle seat end of the tubular body; inserting a needle into a liquid source;  
 withdrawing a selected volume of liquid from the liquid source through the needle and into the tubular body between the needle seat and the stopper while moving the plunger to a fluid drawn position;  
 thereafter inserting the needle into a fluid repository;  
 thereafter applying a second axial force to the plunger to move the stopper toward the needle end of the tubular body while discharging liquid from within the tubular body;  
 engaging a seat/piston latch to axially connect the needle seat with the piston; and  
 relaxing the second force to disengage the needle seat from the generally tubular body and move the piston and the connected needle seat from the initial retained position to the needle seat retracted position.  
 
   
   
     37. A method as defined in  claim 36 , wherein the needle is inserted into the liquid source before moving the plunger to the displaced position, thereby pressurizing the liquid source while the plunger moves to the displaced position. 
   
   
     38. A method as defined in  claim 36 , wherein providing a one way valve includes providing one or more ports in the plunger, the stopper covering the one or more ports to close the valve when pressure within the body is greater than pressure within the plunger. 
   
   
     39. A method as defined in  claim 36 , further comprising:
 providing graduations on the tubular body increasing from the needle end toward the plunger end.  
 
   
   
     40. A method as defined in  claim 36 , further comprising:
 moving the plunger to an injection position such that the plunger expands a portion of the generally tubular body to release the needle seat.  
 
   
   
     41. A method as defined in  claim 36 , wherein plugging the needle seat end of the tubular includes supporting a needle on the tubular body and plugging the needle with a plug, and removing the plug in the needle seat end of the tubular body includes removing the plug from the needle. 
   
   
     42. A method of using a syringe with a needle seat supporting a needle retractable in a generally tubular body having an internal throughbore extending between a needle end and an opposing plunger end, the method comprising:
 sealingly engaging the needle seat with the generally tubular body, the needle seat being selectively movable from an initial retained position to a needle seat retracted position;  
 releasably retaining the needle seat in the initial retained position;  
 axially securing a stopper to a plunger within the throughbore of the tubular body; positioning the plunger at least partially within the throughbore of the tubular body, the plunger including an internal chamber therein;  
 positioning a piston within the plunger moveable from an initial position in the needle end of the plunger to a retracted position within the internal chamber in the plunger;  
 providing a one-way valve between the internal chamber in the plunger and the throughbore of the generally tubular body;  
 plugging the needle seat end of the tubular body;  
 applying a first axial force to move the plunger from an initial position in the opposing plunger end of the tubular body to a selected displaced position, thereby creating a vacuum within the tubular body between needle end of the tubular body and the stopper and opening the one-way valve to obtain a vacuum within the plunger;  
 removing the plug in the needle seat end of the tubular body, thereby closing the one-way valve;  
 inserting a needle into a liquid source;  
 withdrawing a selected volume of liquid from the liquid source through the needle and into the tubular body between the needle seat and the stopper while moving the plunger to a fluid drawn position;  
 thereafter inserting the needle into a fluid repository;  
 thereafter applying a second axial force to the plunger to move the stopper toward the needle end of the tubular body while discharging liquid from within the tubular body;  
 engaging a male member on one of the piston and the needle seat with a female member on the other of the piston and the needle seat to axially connect the needle seat with the piston; and  
 relaxing the second force to disengage the needle seat from the generally tubular body and automatically move the piston and the connected needle seat from the initial retained position to the needle seat retracted position.  
 
   
   
     43. A method as defined in  claim 42 , wherein the needle is inserted into the liquid source before moving the plunger to the displaced position, thereby pressurizing the liquid source while the plunger moves to the displaced position. 
   
   
     44. A method as defined in  claim 42 , wherein plugging the needle seat end of the tubular includes supporting a needle on the tubular body and plugging the needle with a plug, and removing the plug in the needle seat end of the tubular body includes removing the plug from the needle. 
   
   
     45. A method as defined in  claim 42 , wherein movement of the plunger to a full injection position releases the piston from the retained position on the plunger. 
   
   
     46. A method as defined in  claim 42 , wherein providing a one way valve includes providing one or more ports in the plunger, the stopper covering the one or more ports to close the valve when pressure within the body is greater than pressure within the plunger. 
   
   
     47. A method as defined in  claim 42 , further comprising:
 providing graduations on the tubular body increasing from the needle end toward the plunger end.  
 
   
   
     48. A method as defined in  claim 42 , further comprising:
 moving the plunger to an injection position such that the plunger expands a portion of the generally tubular body to release the needle seat.  
 
   
   
     49. A method as defined in  claim 42 , further comprising:
 moving the plunger to an injection piston such that the plunger moves a seal between the seat and the tubular body to release the needle seat.  
 
   
   
     50. A method as defined in  claim 42 , further comprising:
 engaging the piston with the needle seat to release the piston from the plunger to move the piston axially away from the needle end of the plunger.